Hydraulic lift for forward-tilting cabs



Dec. 22, 1942. H, E, SP1-:AR

HYDRAULIC LIFT FOR FORwARD-TILTING @ABS Filed NOV. l2, 1941 2Sheets-Sheet 2 INVENTOR. HERBERT E. 5735A?? A TTONE'Y atenlecl RAUM@ LFUR FURWARD-TRTING i" tu s Herbert 1E. Spear, Detroit, Meh., assigner toShell Development Company, San Francisco, Calif., a corporation oflDelawai-e Aapplication November 12, 19M, Serial No. 418,725

l Claims. (Cl. 1mi-89) This invention relates broadly to motor vehiclesand more specifically to improvements in commercial vehicles of thetilting cab type.

ln the transportation industry there has been a tendency to carryincreasingly larger payloads, thus requiring the use of larger motortrucks. As a result of this demand motor trucks of unusually long wheelbases have been produced. However, such vehicles have been found wardportions of the cab I are Fig. 2 is a diagrammatic view of theelectrical switches and connections therefor; and

Fig. 3 is a longitudinal section of the hydraulic ram and couplingmember therefor, the section `being taken on the line 3-3 of Fig. 1.

With reference to the drawings, a motor vehicle having a cab I and sideframe members ,l is shown in part.' The lower'edge of the forprovidedwith dimcult to operate and maneuver on our presentpintles mounted inbearings xed upon the chasday highway bridges and docks. sis frame 2,the cab being pivotal about the axes With a view of reducing theover-all length oi pintles 3. The rearward portion of the cab of thetrucks without decreasing the payload or rests upon a Supporting brackett Xed upon a carrying capacity space it has become fairly stanchion orframe cross member 5. common practice in certain localities to mount AteleScOpiC hydraulic I'am is pvotally etthe cab or driving compartmentat the forward tached adjacent its lower end to a hollow trunend of thechassis. One of the disadvantages of nion member 1, pivotally mountedupon the supsuch an arrangement is that the accessibility portingbracket l- The upper end 0f Said ram to the engine is greatly reduced.Therefore, is attached to a bracket 9 on the rear Wall I Il variousmeans and methods have been devised of the cab l by means of a universaltrunnion 8. for removing the can from its position over the A hydraulicreservoir Il and a pump i2 driven engine in order to overcome thisdimculty. Prior by an electric motor I3 are mounted on the chasartdevices have failed to awaken much comsis of the vehicle. 'I'hereservoir is provided with mercial interest because of the great amountof a pipe It. Which leads t0 the Dump |2- A Pipe manual eort and lengthof time required to I5 leads from thepump t0 a f0uI-WaY Valve l5 operatesuch devices. 'I'he telescopic ram t-is more fully understood It is anobject of the present invention to proby reference t0 Figure 3 0f thedrawings. The nde mechanical means for tilting the cab oi' the ramconsists essentially of two telescopically .ao-called cab-oVer-enginevehicles. slidable cylinders 6C, @D and a tube 6E. The Another object ofthis invention is to eliminate tube @E has en inner tube 6F which doesnot or reduce the manual effort and time required in move with relationto tube 6E, but serves to contilting the cab. duct the huid to the upperend of piston BB Another object is to provide means whereby when the cub1S being raised es 1S mure fully eX- the cab may be tilted to any degreethin a. plained later herein. 6E and 6F terminate at given maximum andremain at any desired attitheir lower end in the trunnion i and at theirA tude for an indefinite period of time. upper ends -iu the piston 6B.Although the up- .A still further object of this invention is to Der end0f cyliuders'C and 6D are not Shown provide means whereby the maximumdegree of in Figure 3 it Will be appreciated by those Skilled tilting 1Sautomatically limited 1 in the art that the cylinder 6C is closed at itsAnother object is to provide tilting means fm. 4o upper end and thatcylinder 6D has an opening a cab utilizing a source of power entirelyindeat its @per end' The trunnion member 7 Ymndem of the engine of thewhich serves as the base of the ram and is provided with two separatepassages therein for conduct- .llnother object of this invention is toprovide in n md to and fr the r m O ith a cab and its tilting mechag qom a ne passage m @Mmmm W t5 nneets to the tube tE and the other to tubeer' nlsm the mammum amount of accessibility to leading to the top ofPisten 6B the power plant of the vehicle as well as the ac- A pipe n,.with a section of exble pressure cessories and chassis parts locatedunder the hose m s connected to the trunnion member 7 cubwhere Huidcommunication is provided with the Other objects together With uumerusdram t. The ram is also provided with a section remates @rent in theinvention will appear or nenbie pressure hose is and a pipe 2n which yin the following description.' is connected to the four-way valve IE. Apipe 22 in the drawings: having a pressure relief valve 2t therein com-Fig. l is a side elevation oi a cab in a tilted municates with the pipele at a point interpositlon; f

mediate the pump and reservoir for the purpose of lay-passing fluid tothe reservoir when the pressure rises above a predetermined standard.The cab is tilted forward under the influence of pressure fluid exertedupon the pistons within the ram.

The forward tilting movement of the cab is ar rested at a predeterminedposition by means of a limiting switch 2li which opens the electricalcircuit, thereby cutting off the motor I3 and pump i2. Any of the wellknown types of linuting switches, such as the mercury filled type orpendulum types, or the like, may be used for this purpose. The ram 6 isoperated by fluid under pressure delivered through the pipe 2li whichenters cylinders 6C and 5D (Fig. 1), forcing pistons 6A and 6B, whichare connected to cylinder 6D and tube 6E respectively, to their extendedposition, thereby lifting the rear end of the cab i upward and forward.The fluid passes from cylinder BD to cylinder 6C through an opening inthe top of cylinder 6D. The four-way valve 'Iii is provided with ahandle 26, the adjustment of which in a downward or neutral positionperforms two simultaneous functions, namely that oi" cutting off theflow of fluid between the ram it and the other parts of the fluid systemand moving a double pole switch 2l to its open circuit position, whichcuts o the current to the motor. A further downward movement of thehandle 2t places pipes 2D and il in iiuid communication with pipes 2land l5 respectively and, at the same time, closes the double pole switch21 which, in turn, closes the electrical circuit to the limiting switch25 and the motor i3. This causes the pump-to force the iiuid to nowthrough the pipe it to the four-way valve and thence througnpipes il andlli to the hydraulic ram. The fluid enters said ram through the tube @Ewhence it flows through a duct into the chamber defined by the cylinderGD and tube 6E, where it forces cylinder 6D downward, thus tilting thecab backward and downward about the axes of the pintles 3 until itreaches a point where the center of gravity of the cab l has passed thevertical center of the pintles. At such predetermined position, thelimiting switch 25 opens the electrical circuit stopping the motor andpump. The weight of the cab causes the further downward movement thereofuntil a. ball socket 2B in the bottom of the cab is seated upon a ball2li which carries the weight or" cab in its lowered position. As the cabtilts haelt ward and downward, the fluid is forced from cyl inders C andGD through pipes id and to the iour-way valve i6 and thence through pipe'to reservoir il.

Jis the cab tilts forward and upward, the in the space between thecylinders lli exhausted by piston 6B and thi, .i i., s lll and iiithrough the ourway vaive and, thence through pipe 2l to reservoir i.

Under certain seldom encountered such as for example when truel; e abovedescribed cab tilting device s a steep incline which would interieoperation of limiting switches 2li and be desirable to tilt the cabmanually', i, the action of limiting switches a u il. this purpose,switch itil is provided., the cios oi which short-circuits limitingswitches 2d and The extent to which the cab tilts may then ins, ng theUrlred on t may M ,")Till be controlled entirely by four-way valve iiiand acces/ia the co-operating double pole switch 2l. Pres'- sure reliefvalve 23 serves as a safety valve in this instance to relieve excessivepressure developed in pipe l5, in the event that the cab should becarelessly tilted to the maximum extension point of ram E.

Although the foregoing description is necessarily of a detailedcharacter, in order that the invention may be completely set forth, itis to be understood that the specific terminology is not intended to berestrictive or conflining, and that various rearrangements of parts andmodiiications of detail may be resorted to without departing from thescope or spirit of the invention as herein claimed.

I claim as my invention' 1. In a motor vehicle embodying the chassisframe, an engine and a cab pivotally mounted upon the frame above theengine, mechanism for tilting said cab comprising a stanchion mountedupon said frame rearwardly of said engine, a trunnion in said stanchionsuperjacent the top of said engine, a hydraulic ram connected to saidtrunnion and with the rearward portion of said cab, a pump for actuatingsaid ram, and electrically operated mechanism for actuating said pump. i

2. In a motor vehicle embodying a chassis frame, an engine and a cabpivotally mounted upon the frame above the engine, mechanism for tiltingsaid cab comprising an arched stanchion spanning said chassis frame andanchored thereon, the central portion of said stanchion being disposed.above the top of said engine, a piston, a cylinder therefor pivotallymounted upon the rearward portion of the cab, the free end of said cylinbeing disposed above the central portion of said stanchion when thepiston is in its retracted position, a pivotal connection between saidpiston and the central portion of said stanchion, a pump, mechanism foroperating said pump and fluid connections between said pump and saidcylindex' for operating said piston in either direction.

3. In a motor vehicle embodying a chassis frame, an engine and a cabpivotally mounted upon the frame above the engine, mechanism for tiltingsaid cab comprising a cylinder pivotally mounted upon said cab, a pistontherein, a piston rod therefor having fluid passage therethrough, acoupling member secured to said rod and pivotally mounted upon astanchion, and a pump, said coupling member having a passageway thereinin fluid communication with the passage in said rod, and flexibleconduits uniting said pump with said coupling.

fi. a motor vehicle embodying a chassis frame, an engine and a cabpivotally mounted upon the frame above the engine mechanism for tiltingsaid cab comprising a cylinder, a piston therein, pivotal mountingsconnecting said cylinder and piston with said cab and said frame, anelectric motor, a pump driven thereby, fluid conduits between said pumpand said cylinder, a pair of electric switches in said cab coupled withsaid. electric motor and means in said switches responsive to theangular attitude of said cab to the horizontal plane forautomaticallymaking and breaking the electric circuit of said electricmotor.

I-ERBERT E. SPEAR.

